SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2590b09d7226f9016afaf251fd1adcdac68a5e093d55044cda3c3fb85c135781' 
  AND token = 'S9jgPd3d6pWPpep01YEo86NdH4OQXN02m9GYA7T9/lk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}